Partial pressure

In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature.[1] The total pressure of an ideal gas mixture is the sum of the partial pressures of the gases in the mixture (Dalton's Law).

In respiratory physiology, the partial pressure of a dissolved gas in liquid (such as oxygen in arterial blood) is also defined as the partial pressure of that gas as it would be undissolved in gas phase yet in equilibrium with the liquid.[2][3] This concept is also known as blood gas tension. In this sense, the diffusion of a gas liquid is said to be driven by differences in partial pressure (not concentration). In chemistry and thermodynamics, this concept is generalized to non-ideal gases and instead called fugacity. The partial pressure of a gas is a measure of its thermodynamic activity. Gases dissolve, diffuse, and react according to their partial pressures and not according to their concentrations in a gas mixture or as a solute in solution.[4] This general property of gases is also true in chemical reactions of gases in biology.

  1. ^ Charles Henrickson (2005). Chemistry. Cliffs Notes. ISBN 978-0-7645-7419-1.
  2. ^ "Partial pressure - liquids - Nexus Wiki".
  3. ^ Collins, J. A.; Rudenski, A.; Gibson, J.; Howard, L.; O'Driscoll, R. (2015). "Relating oxygen partial pressure, saturation and content: The haemoglobin–oxygen dissociation curve". Breathe (Sheffield, England). 11 (3): 194–201. doi:10.1183/20734735.001415. PMC 4666443. PMID 26632351.
  4. ^ Collman, J. P.; Brauman, J. I.; Halbert, T. R.; Suslick, K. S. (1976). “Nature of O2 and CO binding to metalloporphyrins and heme proteins”. Proceedings of the National Academy of Sciences. 73 (10): 3333-3337.
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